Role of alveolar epithelial barrier in the development of pulmonary edema after oleic acid-induced lung injury

Objective To investigate the changes of alveolar epithelial permeability and the capacity of alveolar epithelium to remove alveolar fluid in the rat models of acute lung injury induced by oleic acid.Methods A total of 35 Wistar rats were randomly assigned to the control group(n=7),and the injured group(n=28) in which the lung injury was induced by intravenous injection of oleic acid at the dose of 0.25 ml/kg.The alveolar liquid clearance rate(ALCR),total lung water content(TLW),extravascular lung water content(EVLW) and alveolar epithelial permeability(AEP) were examined in 3,6,12,24 h after injury(n=7 at each time point).Results After lung injury,there was continuous increase of AEP,TLW and EVLW,as well as progressive reduction of ALCR.On 24 h after injury when all changes were most significant,AEP was increased by 68.7%,ALCR was reduced by 49.4%,TLW and EVLW increased by 44.6% and 92.0% respectively,as compared with control group.Conclusion The alveolar epithelial barrier might play a role in the pathogenesis of pulmonary edema in acute lung injury.